The whale shark (Rhincodon typus) is a slow-moving, filter feeding shark and is the largest fish species in existence. Whale sharks as large as 12.6 meters have been measured, and the species is thought to grow even larger. Despite their appeal, very little is known about the basic biology and ecology of whale sharks. For example, little is known about their growth rates, maturation size or age, reproductive output, lifespan, or locations of breeding or birthing grounds. Estimates of global whale shark populations are unreliable and range widely from about 25,000 to 500,000 individuals.
While whale sharks are often observed feeding near the ocean surface, they are capable of diving to depths of more than 1000 meters. Since they have gills, and do not need to resurface for air, they can remain at significant depths for extended periods of time. This makes traditional scientific methods of estimating population size based on observation unreliable. Moreover, whale sharks reside throughout the tropics, and may not be restricted to living near coral reefs where observations can yield reliable population estimates for other species. Such a large geographical distribution complicates estimating global population, which in turn prevents conservation and management agencies from developing effective plans.
Understanding the movement patterns of large migratory species, such as whale sharks, great white sharks, tuna, and whales, is a critical step toward implementing effective management plans. Obtaining information about the movements of these species would open a window into behaviors never before observed and, through effective management plans, could result in population gains that would allow certain species to escape their endangered or threatened statuses. Understanding movements of these species could also benefit local economies situated near migratory pathways, which could attract sustainable eco-tourism revenue, and a portion of that revenue could be used to sustain effective management plans.